a(n) = product{k=1 to n} (k-th integer from among those positive integers which are coprime to (n+1-k)).

A130767

a(n) = product{k=1 to n} (k-th integer from among those positive integers which are coprime to (n+1-k)).

Terms

    a(0) =1a(1) =2a(2) =9a(3) =40a(4) =420a(5) =2700a(6) =56595a(7) =419328a(8) =8820900a(9) =88488400a(10) =2327925600a(11) =38767286880

External references